There is a close association among trait anxiety, sleep quality, and physical activity (1–3). Studies have shown a bidirectional relationship between sleep quality and anxiety (4, 5)—anxiety can trigger various sleep problems, while poor sleep quality is a significant risk factor for anxiety onset (6), further aggravating internalizing symptoms and creating a vicious cycle. As one of the most common psychological disorders, anxiety is prevalent among college students, with detection rates significantly higher than those in the general population (7). In China, the anxiety detection rate among university students continues to rise, reaching 31% (8). Trait anxiety refers to a relatively stable tendency to experience anxiety over time (9). Abnormal emotional processing and neural activity patterns—such as dysfunctions in the anterior insula and dorsal anterior cingulate cortex—may heighten sensitivity to threat-related stimuli (10, 11). Elevated anxiety levels promote the release of stress-related hormones such as adrenaline and cortisol, disrupt central nervous system functioning, and lead to neurotransmitter imbalances (e.g., glutamate, GABA), all of which impair sleep regulation (12, 13). These physiological disruptions have been shown to correlate closely with impaired sleep quality (e.g., decreased sleep efficiency and prolonged sleep latency) (14). According to the biopsychosocial model (15), individuals with high trait anxiety often experience chronic physiological hyperarousal, which interferes with sleep through both psychological pathways (e.g., persistent worry) and biological mechanisms (e.g., dysregulated cortisol rhythms). The combination of anxiety and poor sleep quality is also associated with worse treatment adherence, a higher risk of acute deterioration, and increased mortality rates (16). Moreover, recent neuroimaging studies have revealed that sleep deprivation can enhance neural reactivity in emotion-related brain regions (e.g., the amygdala and insula) in individuals with high trait anxiety, thereby exacerbating the anxiety–sleep disturbance feedback loop (17).

Meanwhile, physical activity has been widely recognized as an effective strategy for emotional regulation (18). Prior research suggests that trait anxiety may impair sleep quality via heightened stress responses and disrupted neuroregulatory mechanisms, such as HPA axis dysregulation and neurotransmitter imbalance (e.g., glutamate and GABA) (19, 20). Conversely, physical activity helps mitigate anxiety and improve sleep through both stress-buffering and neurobiological pathways (21, 22). Observational studies and meta-analyses (23, 24) have shown that regular moderate-to-vigorous exercise is associated with reduced anxiety onset and enhanced sleep quality (25–27). Exercise contributes to emotional and sleep enhancement through multiple mechanisms, such as regulating the hypothalamic–pituitary–adrenal (HPA) axis, increasing serotonin and endorphin levels, and reducing stress hormones like cortisol (28–30). Ample evidence also suggests that regular physical activity improves sleep efficiency, shortens sleep latency, and increases total sleep duration (22, 31).

Although current research generally supports the positive effects of physical activity in improving anxiety and sleep, there is still no consensus on the optimal intervention format regarding exercise dosage—namely, intensity, frequency, and duration. Some studies suggest that moderate-intensity exercise is most effective (32), while others emphasize the advantages of high-intensity interval training (33, 34). Discrepancies in the effects of exercise duration, frequency, and type remain unresolved (35, 36). Moreover, sleep quality is a multidimensional construct, comprising sleep efficiency, latency, duration, and disturbances. Many existing studies have focused only on total PSQI scores, neglecting the possible heterogeneity between anxiety and different sleep subcomponents (37). In addition, little attention has been paid to the moderating role of demographic variables in these relationships. These limitations reduce the explanatory power of current evidence and hinder the development and dissemination of personalized intervention strategies across populations.

To address the above limitations, it is essential to further explore the specific pathways through which physical activity influences the relationship between trait anxiety and sleep quality. This study aims to fill these gaps from two perspectives. First, it will examine the associations between trait anxiety and various subcomponents of sleep quality to identify which aspects of sleep are most impaired among individuals with different levels of anxiety. Second, it will assess whether physical activity dosage moderates the relationship between trait anxiety and sleep quality, with particular attention to the moderating effects of exercise intensity, frequency, and duration. Given the heterogeneity of the college student population, key demographic variables will be controlled to enhance the explanatory power and generalizability of the findings. Unlike previous studies that have focused solely on overall sleep quality or simple correlations, this research employs a moderation model to systematically analyze the interaction mechanisms among the three variables.

Therefore, this study focuses on clarify the moderating role of physical activity in the relationship between trait anxiety and sleep quality among college students and to investigate how different levels of exercise dosage influence this effect. Specifically, the study proposes the following research questions and hypotheses: (1) college students with different levels of trait anxiety show significant differences in overall sleep quality and its subdimensions; (2) scores of sleep quality subcomponents are positively correlated with levels of trait anxiety; and (3) the intensity, frequency, and duration of physical activity significantly moderate the relationship between trait anxiety and sleep quality, with the strength of moderation varying by dosage. These hypotheses are grounded in neurobiological mechanisms described above, particularly the role of PA in modulating anxiety-related stress responses and sleep regulation. Based on a large-sample cross-sectional dataset and drawing upon previous research, this study aims to identify which subdimensions of sleep quality are impaired in students with high trait anxiety. It further seeks to elucidate how different levels, intensities, durations, and frequencies of physical activity modulate the association between trait anxiety and specific sleep components. Ultimately, the goal is to determine the most appropriate exercise dosage for students with high trait anxiety, ensuring the precision of exercise-based interventions, and to provide direction for clinical screening and targeted interventions, as well as a theoretical foundation for researchers and university administrators.

This study found that physical activity exerted a significant dose-dependent moderating effect on the relationship between trait anxiety and sleep quality, which aligns with previous research findings (1, 2). The results showed that exercise intensity, duration, and frequency moderated the relationship between trait anxiety and different sleep subdimensions. Specifically, different levels of physical activity positively moderated the associations between sleep quality, time to fall asleep, sleep efficiency, daytime dysfunction scores, and trait anxiety, potentially enhancing their interaction. High-intensity physical activity had the most pronounced moderating effect on the associations between trait anxiety and sleep efficiency, sleep quality, and daytime dysfunction. Longer exercise durations were associated with stronger moderating effects on trait anxiety and sleep efficiency, particularly when the duration exceeded 60 minutes. More frequent physical activity showed stronger moderating effects on trait anxiety and sleep quality, sleep latency, and daytime dysfunction, with the most significant effects observed in those exercising more than three times per week. These results are consistent with the findings of Korman et al. (49), who suggested that high-intensity interval training benefits both cardiorespiratory health and emotional regulation. Their experimental study also supported the value of high-frequency exercise (25), demonstrating that adolescents who engaged in running every weekday for three consecutive weeks experienced significant improvements in both subjective and objective sleep metrics, along with enhanced psychological functioning. The current findings extend this evidence to the college student population, highlighting that high-intensity, long-duration, and high-frequency physical activity not only improves sleep but also plays a crucial role in anxiety regulation. This dose-dependent effect may be driven by several neurobiological mechanisms. On one hand, physical activity can regulate hypothalamic–pituitary–adrenal (HPA) axis function, reducing abnormal cortisol secretion caused by trait anxiety, thus alleviating hyperarousal and sympathetic overactivation (50). On the other hand, exercise can increase the release of serotonin (5-HT) and endorphins, thereby improving emotional state and sleep quality. Notably, the rise and subsequent rapid drop in body temperature after high-intensity exercise may activate deep relaxation mechanisms, facilitating the onset of deep sleep (51). Therefore, adequately dosed physical activity may serve as a promising strategy for anxiety intervention and sleep promotion.

Social psychology research suggests that completing high-intensity physical activity can enhance individual psychological resilience and self-efficacy, facilitating the positive transformation of negative mental states (52). High-intensity exercise helps college students with trait anxiety better alleviate anxiety, improve sleep efficiency and quality, and reduce daytime dysfunction. In contrast, low-intensity exercise may be insufficient to trigger the physiological and psychological changes necessary for improving mood and sleep (49), indicating that sufficient exercise load is essential for reducing trait anxiety. However, exercise intensity should be adjusted based on individual physical conditions to avoid excessive fatigue and negative emotions caused by overexertion. These findings further support the World Health Organization’s physical activity guidelines (53), suggesting the need for future integration of evidence from both biological and behavioral research. Moreover, sustained physical activity can help anxious students shift attention away from unpleasant stimuli or physical discomfort, thereby improving their overall emotional state. Long-duration exercise can also regulate and extend slow-wave sleep (SWS), which is particularly important for memory consolidation, physical recovery, and emotional regulation (54). Continuous exercise not only enhances central nervous system function and regulates monoamine neurotransmitters and their receptors, but also improves physical fitness, blood circulation, and cardiopulmonary function, optimizing oxygen delivery during sleep and thereby improving sleep efficiency. Notably, some studies suggest that exercise durations of 20–60 minutes are most beneficial for emotional improvement (2). This difference may be due to the physical capabilities of college students, who may require longer activity durations to experience the same benefits. Additionally, the benefits of physical activity may involve delayed and threshold effects, suggesting that very short durations may not fully produce the intended positive outcomes. Converging evidence also shows that exercise can reduce negative emotions and maintain its effects for up to 24 hours after cessation (2). The regularization of physical activity behavior promotes gradual adaptation and cumulative benefits, supports the development of structured routines, and fosters a more positive lifestyle.

In addition to the dose–response effects, this study verified the significant positive correlations between trait anxiety and the subdimensions of sleep quality, particularly among college students with moderate to high levels of trait anxiety, who exhibited more pervasive sleep problems. Students with low trait anxiety consistently scored better across all sleep subdimensions than those in the moderate trait anxiety group, while the moderate group, except for the use of sleeping medication, outperformed the high trait anxiety group. These findings are supported by previous epidemiological studies (20, 55, 56), which have demonstrated that anxiety exerts a direct and substantial impact on sleep quality, independent of comorbid depression (57). Higher anxiety levels are often associated with excessive sympathetic nervous system activation, resulting in prolonged sleep latency, frequent nocturnal awakenings, reduced deep sleep, and increased daytime dysfunction, all of which impair sleep quality and contribute to sleep disorders (58). Furthermore, the manifestations of sleep disorders differ depending on the severity of anxiety. Sleep and anxiety share overlapping neural networks; with increasing anxiety, brain regions responsible for emotion and stress regulation—such as the amygdala, insula, and anterior cingulate cortex—exhibit hyperactivation, further exacerbating sleep disturbances (59, 60). Simultaneously, decreased connectivity between the medial prefrontal cortex (mPFC) and the amygdala reflects impaired top-down regulation, which not only worsens anxiety symptoms but also alters sleep architecture and degrades sleep quality (61). These problems often form a negative feedback loop, wherein individuals with high anxiety levels worry excessively about insufficient sleep and its consequences, resulting in greater emotional distress and maladaptive behaviors that interfere with sleep onset and maintenance (62). Prolonged psychological stress may also reduce the duration of slow-wave sleep (SWS) (63), thereby lowering sleep efficiency, shortening total sleep time, and gradually increasing reliance on sleeping medications. However, the low trait anxiety group reported fewer instances of sleeping medication use compared to the moderate and high anxiety groups, between whom there was no notable difference. This may be because individuals with lower anxiety experience milder sleep disturbances and are thus less dependent on pharmacological aids, while those in the moderate and high anxiety groups face comparable physiological and psychological stress, leading to similar levels of medication reliance. This finding highlights the importance of implementing comprehensive intervention strategies when addressing sleep problems in individuals with moderate or high trait anxiety, with the aim of reducing reliance on sleeping medications, improving sleep quality, alleviating anxiety symptoms, and minimizing potential drug-related risks.

Sleep quality is a critical factor associated with trait anxiety in college students, and its decline may serve as an independent predictor of psychiatric disorders. Neurobiological studies have shown that as trait anxiety increases, the level of autonomic nervous system activation also rises, leading to dysregulation of the endocrine system and promoting the release of stress hormones such as adrenaline and cortisol. This hormonal imbalance disrupts central nervous system function and alters sleep architecture. Anxiety is also known to disrupt neurotransmitters such as glutamate and gamma-aminobutyric acid (GABA), further weakening effective communication between the central and peripheral systems (13). Moreover, in individuals with trait anxiety, the levels of pro-inflammatory cytokines increase with rising anxiety, amplifying inflammatory responses and affecting the production of critical hormones such as serotonin and melatonin (64). These hormones play a vital role in maintaining regular sleep cycles and may impact sleep onset latency, sleep duration, sleep efficiency, nocturnal awakenings, and daytime functioning. As a result, the restorative functions of sleep are impaired. In turn, sleep disturbances damage neural plasticity and stress-related immune pathways, potentially leading to exacerbated anxiety symptoms or other psychiatric conditions (55, 65, 66). Therefore, to prevent the onset and progression of trait anxiety and sleep disorders, more attention should be directed toward monitoring sleep quality in individuals with elevated anxiety. Particular emphasis should be placed on tracking the use of hypnotic medications as an early warning sign.

The significance of this study lies in its exploration of physical activity as a moderating variable in the relationship between various dimensions of sleep quality and trait anxiety. The findings clarify how different levels, intensities, durations, and frequencies of physical activity influence the association between trait anxiety and specific dimensions of sleep quality. Additionally, the study reveals how sociodemographic factors shape the moderating effects of physical activity. These results underscore the importance of the “dose-response effect” of exercise in emotional research and contribute to refining the behavioral mechanisms by which exercise promotes mental health. However, as this study employed a cross-sectional design, the moderating effects of physical activity on sleep quality and trait anxiety cannot confirm causal relationships. It remains possible that pre-existing sleep problems or high levels of anxiety may inhibit an individual’s motivation and willingness to engage in physical activity, thereby influencing their activity levels (67). Future research is encouraged to adopt longitudinal tracking or experimental intervention designs to further elucidate the causal pathways and dynamic relationships among physical activity, sleep quality, and trait anxiety over time.

Higher levels of trait anxiety are associated with poorer overall sleep quality and greater impairments across all sleep subdimensions among college students. Physical activity significantly alleviates anxiety and improves sleep, with stronger moderating effects observed at higher intensity, longer duration, and greater frequency. This study highlights the “dose-response effect” of physical activity and recommends that universities promote high-intensity, long-duration, and frequent exercise interventions to prevent and address mental health issues.